Description: Cytokines play important roles in the regulation of cell growth, differentiation, immune and inflammatory responses. Cytokines can activate multiple signal transduction pathways to regulate gene expression. STATs and NF-kB are two important families of transcription factors that are activated by cytokines. Abnormal regulation of STAT and NF-kB activities has been associated with human diseases. The long-term goal of my laboratory is to study the regulation of cytokine-triggered gene activation pathways. We have identified and characterized a family of proteins named PIAS (protein inhibitor of activated STATs), which can regulate the transcriptional activity of STATs in response to a variety of cytokines. Most recently, we found that PIAS is also involved in the regulation of NF-kB activity. The overall goal of this research proposal is to study the regulation of cytokine-triggered gene activation pathways by the PIAS family of proteins using biochemical and genetic approaches. First, we will study the regulation of the PIAS protein family. Specifically, we will identify and characterize cytokine-induced PIAS1 modification using mass spectrometry analysis and mutational studies. The biological role of PIAS1 modification in the regulation of cytokine signaling will be examined at various levels. Second, we will study the mechanism of PIAS-mediated gene regulation through the identification and characterization of PIAS-associated proteins. We will examine the functional role of the PIAS SAP domain in PIAS-mediated gene regulation using biochemical and mutational studies. Third, we will continue characterizing the in vivo role of PIAS1 in cytokine signaling. The specificity and redundancy of PIAS in cytokine signaling will be examined by genetic approaches. A mutant PIAS1 knockin mouse model will be generated to examine the physiological role of PIAS1 SUMO ligase activity in cytokine signaling. These studies will provide important information on the understanding of the cytokine-triggered gene activation pathways and will enhance our ability to design rational therapeutic strategies employing cytokines. [unreadable] [unreadable]